Description: Painting of black and white contrasted lines that appear to vibrate and form three-dimensional depressions in a "S" shaped pattern. In this and other early works, Riley "wanted the space between the picture plane and the spectator to be active." She later explored color contrast.

Description: Painting of black and white contrasted polka-dots that appear to vibrate and form three-dimensional depression at the center of the piece. In this and other early works, Riley "wanted the space between the picture plane and the spectator to be active." She later explored color contrast.